Degree Date: December, 2014
Ana Malagon's picture
Ana Malagon
O. Keith Baker

Search for 140 microeV Pseudoscalar and Vector Dark Matter Using Microwave Cavities
Dark matter plays an important role in structure formation and composes 26.8% of the total energy density in the universe. There are many postulated particles that are theorized to be the constituents of cold dark matter; however, none have been observed experimentally. One strongly motivated particle that could be cold dark matter is the axion, a pseudoscalar with a two photon vertex. Experimental techniques to detect dark matter axions rely on a multiphoton radiative transition; in the... more
Gennady Voronov's picture
Gennady Voronov
George Fleming
Applied Scientist


The Extent of the Two-Color Fundamental Conformal Window
The $SU\!\left(2\right)$ gauge theories with $N_{f}$ flavors of massless vector-like Dirac fermions transforming in the pseudo-real fundamental representation have an enhanced global chiral symmetry and a distinct symmetry breaking pattern. These theories are expected to be qualitatively different from quantum chromodynamics (QCD) in the infrared (IR), especially with respect to the properties of the Nambu-Goldstone bosons (NGB). Having the potential to elucidate many features of both known and... more
Liyao Wang's picture
Liyao Wang
Mokshay Madiman

Heat capacity bound, energy fluctuations and convexity
In classical statistical mechanics, the heuristic that in the canonical ensemble the energy distribution is sharply peaked at the mean energy is crucial in justifying the equivalence between the canonical and microcanonical ensembles. It turns out that this is closely related with the fundamental notion of a typical set and the Shannon-McMillan-Breiman theorem in information theory. In this dissertation, we explore the connections between the two and establish some new rigorous results that are... more
Degree Date: May, 2014
Colin Bruzewicz's picture
Colin Bruzewicz
David DeMille

Continuous Optical Production of Ultracold Vibronic Ground State Polar Molecules
Polar molecules present an exciting new test bed for ultracold physics with applications in numerous fields, such as chemical reaction dynamics, many-body systems, and quantum computation. Creating large samples of these molecules that can be trapped for long times, however, remains an ongoing challenge. We demonstrate the direct formation of vibronic ground state RbCs molecules by photoassociation of ultracold atoms followed by radiative stabilization. From analysis of the relevant free-to-... more
Bernard Hicks's picture
Bernard Hicks
Helen Caines

Differential Production Cross-Section of Heavy-Flavor Electrons in √s = 2.76 TeV pp collisions at the LHC with the ALICE detector
Recent results at RHIC seem to confirm T.D.Lee’s hypothesis that a new form of matter, the quark- gluon plasma (QGP), could be formed in heavy-ion collisions at high energies. Heavy quarks, being formed in the early stages of heavy-ion collisions, form a good probe for the properties of the QGP. The energy loss of heavy quarks as they traverse the medium is predicted to be less than that of the lighter quarks. However, previous measurements of the nuclear modification factor at RHIC... more
Lawrence Lee's picture
Lawrence Lee
Tobias Golling
Postdoctoral Fellow

Harvard University

A Search for B-violating Supersymmetry in Multijet Signatures at the ATLAS Experiment
With supersymmetry (SUSY) increasingly constrained, more attention is placed on alternate flavors of SUSY that allow for an unexcluded natural theory. A search for new physics phenomena in all-hadronic signatures in \sqrt{s}=8 TeV pp collisions using an integrated luminosity of 20.3 fb^-1 collected by the ATLAS detector at the LHC will be presented. Within the context of SUSY, gluino pair-production gives rise to multijet final states in models that allow for violation of R-parity. Two types of... more
Rongrong Ma's picture
Rongrong Ma
John Harris
Assistant Physicist

Brookhaven National Laboratory

Jet measurements in pp and Pb-Pb collisions in ALICE
Lattice-QCD predicts the existence of a new form of hot, dense matter called the Quark Gluon Plasma (QGP) above a critical energy density. Such matter is believed to be created in relativistic heavy-ion collisions, where sufficient energy is expected to be deposited by colliding ions in a limited volume. To study the properties of the QGP, high transverse momentum (pT) partons produced at the early stage of the collisions are used as probes. Since partons are not directly measurable, jet... more
Tianqi Shen's picture
Tianqi Shen
Corey O'Hern
Quantitative Research

Laurion Capital

Contact Percolation, Fragility and Frictional Packings
This thesis presents four computational and theoretical studies of the structural, mechanical, and vibrational  properties of purely repulsive  disks, dimer-, and ellipse-shaped particles with and without friction.  The first study investigated the formation of interparticle contact networks below jamming onset at packing fraction φJ , where the pressure of the system becomes nonzero.  We generated ensembles of static packings of frictionless disks over a range of... more
Degree Date: December, 2013
John Barry's picture
John Barry
David DeMille

Laser cooling and slowing of a diatomic molecule
Laser cooling and trapping are central to modern atomic physics. It has been roughly three decades since laser cooling techniques produced ultracold atoms, leading to rapid advances in a vast array of fields and a number of Nobel prizes. Prior to the work presented in this thesis, laser cooling had not yet been extended to molecules because of their complex internal structure. However, this complexity makes molecules potentially useful for a wide range of applications. The first direct laser... more
Prasenjit Dutt's picture
Prasenjit Dutt
R. Shankar

Strongly correlated quantum transport out-of-equilibrium
The revolutionary advances in nanotechnology have facilitated the precise control and manipulation of mesoscopic systems where quantum effects are pronounced. Typical experimental settings are capable of driving these systems far from equilibrium, where linear response theory is inadequate. We study transport through quantum-impurity systems in the regime of strong correlations and determine the effects of large temperature and potential gradients on its many-body physics. We introduce a... more
Merideth Frey's picture
Merideth Frey
Sean Barrett
Professor of Physics

Sarah Lawrence College

Using Novel Pulse Sequences for Magnetic Resonance Imaging of Phosphorus-31 in Hard and Soft Solids
Since its invention in 1973, magnetic resonance imaging (MRI) has become an invaluable tool for clinical medicine, fundamental biomedical research, the physical sciences, and engineering. The vast majority of all MRI studies, in medicine and beyond, detect only the signal from a single nuclear isotope, H-1, in liquid water. Extending the reach of MRI to the study of other elements, and to hard or soft solids, opens new frontiers of discovery. In practice, however, the slower motion of the... more
Kurtis Geerlings's picture
Kurtis Geerlings
Michel Devoret
Research Manager

Gentex Corporation

Improving Coherence of Superconducting Qubits and Resonators
Superconducting qubits and resonators with quality factors exceeding 10^7 are of great interest for quantum information processing applications. The improvement of present devices necessarily involves the consideration of participation ratios, which budget the influence of each physical component in the total energy decay rate. Experiments on compact resonators in which participation ratios were varied has demonstrated the validity of this method, yielding a two-fold improvement in quality... more
Aaron Mertz's picture
Aaron Mertz
Eric Dufresne
Director, Science & Society Program

Aspen Institute

Collective Mechanics of Epithelial Cells
Cell–cell and cell–matrix adhesions play essential roles in the function of tissues, yet little is known about how crosstalk between these two adhesion types regulate cells' material properties and active processes. This dissertation combines experiment and theory to reveal how colonies of cells apply forces to the extracellular matrix. Using traction force microscopy, we measure forces transmitted to the substrate by colonies of epithelial cells with strong and weak cadherin-... more
Konstantin Nesterov's picture
Konstantin Nesterov
Yoram Alhassid
postdoctoral research associate

University of Wisconsin-Madison

Mesoscopic Effects in Chaotic Metallic Nanoparticles
We study electron interactions in a nanosized chaotic metallic grain with a large Thouless conductance. We use the so-called universal Hamiltonian, which describes the low-energy physics of such a grain. The noninteracting part of this model fluctuates and is described by random-matrix theory, while its interaction terms are universal and do not fluctuate. Of particular interest are grains in the fluctuation-dominated regime of pairing correlations, where the grain is so small that its single-... more
Alice Ohlson's picture
Alice Ohlson
John Harris

Investigating Parton Energy Loss with Jet-hadron Correlations and Jet vn at STAR
A strongly-coupled, deconfined state of quarks and gluons, known as the Quark-Gluon Plasma (QGP), is created in high-energy collisions of heavy nuclei. The QGP can be probed by high-momentum quarks and gluons (collectively known as partons) that are produced in hard scatterings early in the collision. The partons traverse the QGP and fragment into collimated "jets" of hadrons. Studies of parton energy loss within the QGP, or medium-induced jet quenching, can lead to insights into the... more